Apparatus, system and method for mechanical, selective weed control in mature and establishing crops including turfgrasses

ABSTRACT

A method of improving wear tolerance of desirable plants and reducing weed pressure involves periodically applying mechanical abrasion to the desirable plants and the undesirable plants, wherein the level of mechanical abrasion is selected to be damaging to the undesirable plants and substantially within the wear tolerance of the desirable plants. The desirable plants may include turfgrasses and/or forage grasses. The mechanical abrasion may be applied by a rotating cylindrical brush with bristles engaging a base having a plurality of grooves. In one example, the period of applying mechanical abrasion is about once per week.

RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 120 to U.S.Provisional Patent Application No. 61/929,607, filed Jan. 21, 2014, andto U.S. patent application Ser. No. 14/601,574, filed Jan. 21, 2015, theentire disclosures of which are incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an apparatus useful in reducing weedpressure and/or improving wear tolerance in crops. For example, anapparatus, system and method is provided to improve turfgrass quality,wear tolerance, reduce weed pressure, and for retaining more turfgrasscover when a turfgrass area is subjected to traffic.

BACKGROUND OF THE INVENTION

As used herein, the term “crop” refers to desirable plants, including,in one aspect of the invention, turfgrasses. Turfgrasses are differentfrom other grasses in three primary ways: turfgrasses can form a densecontiguous community, tolerate frequent mowing and tolerate traffic. Dueto these unique qualities turfgrasses are used extensively in our urbanculture including golf courses, athletic fields, parks, cemeteries,roadsides and home lawns. Proper turfgrass management is critical to itslong-term sustainability and the safety of the playing surfaces whereit's utilized. Turfgrass is managed according to five primary culturalpractices; 1) mowing, 2) fertilization, 3) cultivation, 4) irrigationand 5) pest control.

While turfgrasses are often grown as part of an athletic field, golfcourses and/or lawns, other types of grasses may also comprise adesirable crop plant. For example, grasses may be grown for grazing bycattle. Such grasses may comprise forage grasses, turfgrasses, or acombination thereof. Another example of a crop that may also be grownfor harvest is hay.

Pest control employs preventative and/or curative approaches toprotecting desirable crop species, such as grasses, from potentiallydamaging weeds, insects, and/or diseases. Traditionally, turfgrassmanagers have implemented an Integrated Pest Management (IPM) program tomaintain pest populations below threshold levels. The IPM approachallows the judicious use of pesticides to maintain pest populations atan acceptable level to maintain a healthy turfgrass stand. A pesticideis a broad term used to describe any substance that prevents, destroys,repels or mitigates any pest. Pesticides are further categorizedaccording to their intended targets (i.e. herbicides, fungicides,insecticides, etc.). Herbicides, pesticides targeting weeds only,accounted for the highest usage of pesticides in the home and gardensector with 66 million pounds applied in 2007. U.S. EnvironmentalProtection Agency, Pesticides Industry Sales and Usage 2006 and 2007Market Estimates.

The concern regarding pesticide applications has increased tremendously,particularly where there is potential risk of exposure to children suchas lawn areas, athletic fields and parks/playgrounds. The primaryconcern regarding low, nonacute, repetitive and combined exposures areincreased risk of cancer, abnormal neurodevelopment, asthma,perturbation of gestational growth, and endocrine-mimicking effects (USAAP 2012 and Can Fam Phys, 2007). J. R. Roberts, C. J. Karr, PesticideExposure in Children, Pediatrics Vol. 130, No. 6 (2012); K. L. Bassil,et al, Cancer Health Effects of Pesticides, Canadian Family Physician,Vol. 53 (2007). These very serious concerns have resulted in pesticiderestrictions related to athletic fields in 41 out of 50 states,according to the Sports Turf Managers Association. Connecticut hasbanned all pesticide applications on school grounds and athletic fieldsserving grades pre-k through grade 8. There is discussion to expand thescope of this law to high school and public grounds. The state of NewYork passed the Childs Safe Playing Field Act that essentially banspesticide use on schools grounds, day care centers and athletic fieldsthrough grade 12. Additionally, several municipalities across the U.S.have banned pesticides on parks, open space parcels and public rights ofway. This includes 7 states, 18 cities, and 92 parks/playgrounds.Concerns regarding pesticide impacts on human health and the environmenthave even advanced to the university and college level where somecampuses or specific areas of campus have been declared pesticide-freeas they embrace more sustainable approaches.

Turfgrass breeding efforts have resulted in improved cultivars ofdifferent turfgrass species that have better insect and diseaseresistance helping to reduce the susceptibility of some turfgrassspecies. Additionally, entomopathogenic nematodes have been shown tobiologically control some of the most damaging root feeding insects.See, Georgis, R., and R. Gaugler, Predictability in biological controlusing entomopathogenic nematodes. J. Econ. Entomol. 84(3):p. 713-720.However, a consistent method of weed control is not available. Thisleaves many high quality turfgrass areas susceptible to weedinfestations on a perennial basis. This is particularly a concern inhigh traffic areas such as athletic fields where turfgrass cover iscontinually reduced and opportunistic weeds are able to germinate,develop quickly, and potentially dominate a turfgrass stand in a veryshort period of time.

Previous research has investigated the effects of utilizing existingequipment such as spring-tine harrows or vertical cutting units todamage weeds and create a competitive advantage for turfgrasses onfootball pitches. Larsen, S. V., P. Kristoffersen, and J. Fischer,Turfgrass management and weed control without pesticides on footballpitches in Denmark. Pest Manage. Sci. 60(6):p. 579-587. However, thesemethods were thought to be too injurious to the established turfgrassresulting in modest weed control and sometimes increased weed pressure.

Research has shown that perennial broadleaf weeds and annual grassyweeds are less traffic tolerant than desirable turfgrass species.Miller, N. A., and J. J. Henderson 2012, Organic management practices onathletic fields: Part 1: The effects on color, quality, cover, and weedpopulations. Crop Sci. 52(2):p. 890-903 and J. T Brosnan et al, LargeCrabgrass, White Clover, and Hybrid Bermudagrass Athletic Field PlayingQuality in Response to Simulated Traffic, Crop. Sci 54:1838-1843 (2014).Therefore, when intense traffic is applied over time to a turfgrassstand containing perennial broadleaf weeds and annual grassy weeds, thedesirable turfgrasses persist and the weeds do not. Traffic is acombination of wear (i.e. tearing and bruising of leaf tissue) and soilcompaction (i.e. forcing soil solids closer together). Research has alsoindicated that when traffic components (wear and compaction) areimplemented separately to different areas and their detrimental effectsare compared, wear is more detrimental to the quality of vegetativecover than compaction. See, Dest, W. M., J. S. Ebdon, and K. Guillard,Differentiating between the influence of wear and soil compaction andtheir interaction of turfgrass stress, Int. Turfgrass Soc. Res. J. 11(Part 2) p. 1067-1083.

Weeds substantially reduce the aesthetic quality of turfgrass stands,but most importantly are less traffic tolerant than turfgrasses.Therefore, once weeds dominate an existing turfgrass stand, weeds areunable to persist under the constant traffic and vegetative cover isdrastically reduced. Athletic fields with reduced vegetative cover havebeen linked to higher surface hardness values and increased risk ofsurface related injuries. See, Dest, W. M., and J. S. Ebdon. Study:Natural turf use levels. Sports Turf. 27(5) p. 8, 10-11 and Brosnan etal. 2014. However, chemical applications, such as selective herbicides,are more likely to be limited on athletic fields.

Accordingly, there is a need for an apparatus, system and method ofgrowing and improving desirable, wear-tolerant plants and reducingundesirable weeds that may compete with this growth. There is further aneed for an apparatus, system and method of reducing weeds in turfgrassand other crops without the application of selective herbicides. Thereis also a need for an apparatus, system and method of producing improvedwear tolerance in turfgrass.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus, systemand method of growing and improving crops (including turfgrasses) andreducing weeds that may compete with this growth and improve weartolerance.

In one example of the present invention, an apparatus for applying adesired amount of mechanical abrasion to a crop is provided. Theapparatus includes a base, a brush and an elevation device formaintaining the base at desirable height. The base has a firstlongitudinal axis and a plurality of grooves, the grooves being orientedapproximately perpendicular to the first longitudinal axis. The brushhas a second longitudinal axis and a plurality of bristles and/or bladesextending outwardly from the second longitudinal axis. The brush isattached to the apparatus such that the second longitudinal axis issubstantially parallel to the first longitudinal axis and the brush isrotatable about the second longitudinal axis. The brush is spaced fromthe base such that the plurality of bristles engage the plurality ofgrooves. The base is adjustable enabling the operator to move the basecloser or further from the rotating brush/blades.

The elevation device is configured to support the base above the groundbut in contact with the crop. The elevation device may comprise any oneof several structures, including vertically-adjustable rollers, wheels,skids, and combinations thereof. For example, the elevation device maysupport the base such that crops and other plants such as weeds areengaged by the plurality of bristles/blades and drawn into the pluralityof grooves and/or teeth and/or vertically orientated rotating discs.

In one example, the brush is cylindrical. In another example, rows ofbristles may be arranged in a helix. The plurality of bristles willtypically exceed the plurality of grooves and/or vertically orientatedrotating discs. Also, the bristles are typically smaller in diameterthan the width of the grooves and/or vertically orientated rotatingdiscs. The grooves may have a constant width or a tapered width, and maybe textured to increase wear. The base may comprise a single, integratedunit or a combination of a base blade mounted on a blade holder, wherethe grooves are formed on the base blade.

A method of applying a desired amount of mechanical abrasion todesirable plants and undesirable plants is also presented. The methodincludes periodically applying mechanical abrasion to the desirableplants and the undesirable plants, wherein the level of mechanicalabrasion is selected to be damaging to the undesirable plants andsubstantially within the wear tolerance of the desirable plants. Thedesirable plants may include turfgrasses and/or forage grasses. Themechanical abrasion may be applied by a rotating cylindrical brush withbristles engaging a base having a plurality of grooves. In one example,the period of applying mechanical abrasion is about once per week.However, the period of application will vary depending on weed pressure,growing conditions, maturity of the desirable plants, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified.

FIG. 1 illustrates a front view of an apparatus according to one exampleof the present invention, the apparatus being attached to a conventionalmower;

FIG. 2 is an enlarged view of a portion of the apparatus of FIG. 1;

FIG. 3 is a rear view of the apparatus of FIG. 1;

FIG. 4 is a view of a base blade and blade holder of the apparatus ofFIG. 1.

FIG. 5 is an alternate view of a base blade and blade holder of theapparatus of FIG. 1.

DESCRIPTION OF THE EMBODIMENTS

While the invention has been described in detail with respect to thepreferred embodiments thereof, it will be appreciated that upon readingand understanding of the foregoing, certain variations to the preferredembodiments will become apparent, which variations are nonethelesswithin the spirit and scope of the invention.

The term's “a” or “an”, as used herein, are defined as one or as morethan one. The term “plurality”, as used herein, is defined as two or asmore than two. The term “another”, as used herein, is defined as atleast a second or more. The terms “including” and/or “having”, as usedherein, are defined as comprising (i.e., open language). The term“coupled”, as used herein, is defined as connected, although notnecessarily directly, and not necessarily mechanically. The term “or” asused herein is to be interpreted as an inclusive or meaning any one orany combination.

Reference throughout this document to “some embodiments”, “oneembodiment”, “certain embodiments”, and “an embodiment” or similar termsmeans that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the present invention. Thus, the appearances of such phrases or invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments without limitation.

The drawings featured in the figures are provided for the purposes ofillustrating some embodiments of the present invention, and are not tobe considered as limitation thereto. Term “means” preceding a presentparticiple of an operation indicates a desired function for which thereis one or more embodiments, i.e., one or more methods, devices, orapparatuses for achieving the desired function and that one skilled inthe art could select from these or their equivalent in view of thedisclosure herein and use of the term “means” is not intended to belimiting.

As used herein, the term “crop” refers to desirable plants, includingdesirable grasses, including, but not limited to Kentucky bluegrass,perennial ryegrass and combinations thereof, forage grasses, hay, etc.The term “weed” refers to undesirable perennial, biennial and/or annualplants, including broadleaf (dicotyledonous) and grassy(monocotyledonous) species. As used herein the term “traffic” refers toa combination of wear (i.e. tearing and bruising of leaf tissue) andsoil compaction (i.e. forcing soil solids closer together) of theturfgrass. As used herein the term “wear tolerance” refers to theability of plants, including but not limited to desirable grasses, towithstand aggregate, repeated stresses of damage to above ground plantmaterial over a period of time.

As is illustrated in the accompanying FIGS. 1-4, an example of thepresent invention is generally shown as apparatus 100 for operating ondesirable turfgrasses and undesirable weeds. In particular, the presentinvention provides an apparatus, system and method of reducing weedpressure on desirable turfgrasses. Apparatus 100 has a cylindrical brush110; a grooved base 120 and a roller 130 (FIG. 3). Roller 130 is anelevation device, may be configured to be adjustable in a verticaldirection 140 to control the height of the base 120. In FIG. 1, theapparatus 100 is illustrated as being used in conjunction with a ride onmower 160, which may provide power to rotate the cylindrical brush 110and propel the apparatus 100 across a surface, such as a an athleticfield.

Referring to FIG. 1 the cylindrical brush 110 may be configured, forexample in a width of approximately 70 cm and have a 17 cm diameter. Thecylindrical brush 110 may be comprised of a plurality of separate rows.In the example illustrated in FIGS. 1-3, four rows 112 of brushes areused, each being installed on an axle with a 90 degree twist to form ahelix. Other numbers of rows may also be used with appropriateadjustments in the amount of twist on each row of brushes. Each row 112can be comprised of a plurality of nylon bristles 111 each beingapproximately 1.5 mm diameter and having a 5 cm pile height. In theillustrated example, bristles 111 are the same size, however, bristlesof varying diameters may be included in brush 110. Bristle tips may becut or rounded. Also, to further optimize the level of mechanical wear,the bristles may be smooth, textured or micro notched in the vertical orhorizontal plane. In cases where weeds are especially hardy, metalblades may also be included on the brush 110. The blades may be shorterthan the bristles, and the bristles would help bring the weeds intoengagement with the base blade. While a plurality of staples of flexiblebristles are a preferred example of a brush, the terms “brush” and“bristles” as used herein may also include any protrusions (e.g., tines,nubs) configured to impart selective tearing and/or bruising of leaftissue.

The rows 112 are mounted on a shaft 113, which is supported by bearingson either end of apparatus 100. The rows 112 of the bristles 111 can beconfigured in a helicoid (a spiral shape around an axis or cylinder).The arrangement of the bristles 111 and rows 112 allow vegetation orplant material to enter the apparatus 100 and be subjected to therotating bristles 111. The bristles 111 force the plant material intogrooves 121 of the base 120. The grooves 121 of the base 120 aredesigned to: 1) assist the bristles/blades to grasp the undesirableplants and completely remove the plants from the ground (including theroots), 2) increase pressure on the leaf tissue/stem to promote tearingand bruising from bristle action and/or 3) completely remove the leaffrom the stem. Repeated applications at key points during the growingseason exhausts the carbohydrate reserves of the undesirable plants,leading to plant death.

Finally, roller 130 provides variable height of operation and maintainsa desired height 140 of the base 120 during operation. Other elevationdevices may also be used, including wheels, skids, segmented rollers,and combinations thereof. It is preferable, but not necessarilyrequired, for the elevation device to include a mechanism for adjustingthe height of the base.

This apparatus can have multiple configurations to implement this methodof weed control. Configuration examples are as follows; Stand-aloneconfigurations include self-propelled walk-behind and ride-on units. Theapparatus 100 can be used concurrently with a mower (i.e. two separatepieces of equipment operated independently) (not shown) or as anintegrated part configured as a mower attachment, mounted in front,mid-section or rear of an existing mower. This includes ganged units,self-powered pull-behind units, and power take off driven, three pointhitch mounted or pull-type units for tractors. Alternatively, theintegrated part can be designed integral as part of the mower or mowerdeck. In this embodiment, the frame of the apparatus is configured tohold the cylindrical, brush 110 enabling the brush 110 and bristles 111to rotate and interact with the grooved base 120 so as to impart wear onplant material, such as weeds and turfgrasses. In one example of theinvention, the brush rotates. In other examples, the brush may engage ina reciprocating motion. As illustrated in FIG. 1, a belt 115 may drive apulley 116 which is attached to the shaft 113. Alternatively, the shaft113 may be driven hydraulically. The shaft 113 may also be driven bywheels through a gearset as is known with reel-type mowers.

FIG. 2 illustrates a view of how the bristles 111 interact with thegrooves 121. The bristles have a diameter which is smaller than theopening of the grooves, so the bristles may pass through the grooveswithout binding or popping out of the grooves. However, the bristles 111are not precisely aligned with the grooves 121, and enter the grooves atslight angles to the grooves. The bristles 111 consequently rub alongthe sidewalls 122 of the grooves 121 and/or top edges of the grooves. Inone example, the bristles are dimensioned to rub along at least aportion of the bottoms of the grooves 121 as well. One or more bristles111 enter the grooves 121 in a semi-loose state with the plants such asa weed species and/or turfgrass. As the bristles 111 and the smallerweeds (containing leaflets) progress through the grooves 121, thebristles 111 damage leaves and/or stems of undesirable broadleaf plantsby abrading them against the sidewalls 122 of the grooves 121 and/orbottom of the grooves 121. For weed species with broader leafmorphology, the action of the bristles 111 and grooves 121 will interactto tear and bruise leaf tissue. Some weed species may be completelyremoved from the soil. For example, crabgrasses have been observed to beengaged by the bristles and grooves and be uprooted. However, thinnergrass leaves experience less abrasion from the apparatus 100 and aremore tolerant of abrasion. In this respect, the mechanical abrasion ofthe present invention is not the same as mowing (which cuts all plantsequally) or vertical cutting (which is damaging to turfgrass). In oneexample, grooves 121 can be configured to have a depth of 6 mm. Inanother example, the depth of the grooves 121 increases and/or decreasesas the bristles move through the grooves 121.

The base 120 containing grooves 121 can be configured so that the firstportion is a lip 123, for example, approximately 3 cm. Preferably, lip123 is smooth, so that desirable crops may slide off the base afterbeing engaged by the bristles. In a first example, the grooves 121 havea uniform width. In a second example, the grooves 121 taper from a widthof 8 mm to a width of 4 mm. The grooves may be formed when casting thebase 120, by cutting notches into base 120, by welding fins onto base120, or by other methods. The grooves 121 may be various widths andlengths, so long as they cooperate with the brush 110 to applymechanical wear to plants. In another example, the grooves may includesharpen or serrated teeth to increase mechanical tearing of leaves. Inanother example, the base 120 may include counter-rotation slicing discsinterspersed between and parallel with the grooves 121. The slicingdisks spin in the same direction as the brush 110 to rip weed leaves andpull weeds out of the soil.

In the illustrated example, the base 120 comprises a base blade 120 a,which contains the grooves 121, and a blade holder 125, on which thebase blade 120 a is mounted. This allows base blade 120 a to be replacedif necessary, without replacing the entire base. In another example, thebase 120 is a unitary structure with the grooves 121 integrally formedthereon. In another example, the base may be concave, so that thebristles maintain a consistent distance from the grooves.

A prototype has been developed, and results from trials show thatroutine use on established turfgrass stands creates an environmentfavorable for obtaining results of desirable turfgrasses stands anddetrimental to the most troublesome weed species in cool-seasonturfgrasses.

A first study involved the use of the apparatus on Kentucky bluegrass.This is the predominate species utilized on athletic fields and homelawn mixtures where cool-season grasses are utilized. The study includedthree treatments: 1) Weed Defoliator/Extractor once per week, 2)chemical herbicide, and 3) an untreated control, with two replications.Clover populations were evaluated qualitatively utilizing a scale of0-100% weed cover, prior to treatment applications. Plots were treatedwith the Weed Defoliator/Extractor and mowed immediately following,simulating the Weed Defoliator/Extractor device being incorporated intoa mower deck. Plots were qualitatively assessed six weeks laterfollowing seven treatments with the Weed Defoliator/Extractor device.Percent clover control was calculated using the Henderson-Tilton formulawhich utilizes pretreatment weed populations, post treatment weedpopulations and weed populations in the untreated control. Analysis ofvariance was used to test for significant (P≤0.05) differences betweentreatments. Mean separations were conducted using Fisher's leastsignificant difference test with a 0.05 probability level. Treatmentswith the same letter are not significantly different. The apparatus ofthe present invention successfully controlled over 70% of the clover(significantly more than the untreated control). The chemical weedcontrol treatment was applied after the last rating date to maximizeefficacy. However, the efficacy of the chemical treatment will likely be100%.

A second study was conducted on perennial ryegrass and was designed tolook more closely at how to best utilize the Weed Defoliator/Extractordevice in terms of frequency. Perennial ryegrass is another speciesheavily utilized on athletic fields and in home lawn mixtures. The studyincluded six treatments; 1) Weed Defoliator/Extractor once per week, 2)Weed Defoliator/Extractor twice per week, 3) Weed Defoliator/Extractorbiweekly, 4) as needed, 5) chemical herbicide, and 6) untreated controlwith three replications. Clover populations were evaluated qualitativelyutilizing a scale of 0-100% weed cover, prior to treatment applications.Plots were treated with the Weed Defoliator/Extractor and mowedimmediately following. Plots were qualitatively assessed six weekslater. Percent clover control was calculated as described above. Theseresults show that Weed Defoliator/Extractor treatments applied once perweek were most effective for reducing the clover populations. Appliedonce per week, Weed Defoliator/Extractor treatments controlled over 98%of the clover (significantly more than the untreated control). Thechemical weed control treatment was applied after the last rating dateto maximize efficacy. However, the efficacy of the chemical treatmentwill likely be 100%.

The present invention produces an environment advantageous for themonocotyledonous morphology of desirable grasses by imposing a uniform,modest level of wear. The apparatus 100 is configured to provide minimaldisturbance to the existing grass stand and damage only the weeds.Additionally, this apparatus 100 does not disturb the soil surface,unlike spring-tine harrows or vertical cutting units of the prior artthat have disadvantages of exposing additional weed seed that canpotentially germinate and compete with the grass. The apparatus 100 canalso be used to manage weed populations in other turfgrass areas orcropping systems.

Accordingly, the method of the present invention creates an environmentwhere turfgrasses are able to persist and where weeds are not able topersist. For example, the morphology of broadleaf weeds makes them morevulnerable to the action of the apparatus of the present invention;whereas desirable turfgrasses are not unduly adversely affected. Leavesof weeds are much wider and often times more succulent than turfgrasses.The apparatus of the present invention, based on these morphologicaldifferences, damages weeds more than turfgrasses. The damaged weedsrequire regeneration, re-growing and/or rejuvenation thereby allowingthe less damaged turfgrasses to grow and thrive in the place of weeds.

More specifically, once the leaf tissue of the weed species is damagedits ability to absorb the suns energy to produce carbohydrates throughthe process of photosynthesis is greatly reduced or eliminated. As theapparatus 100 of the present invention is used, the weed leaf tissue isdamaged or removed with repeated and regular use. The weed will need torely on carbohydrate reserves in the root system for recovery andgrowth. This reserve supply will eventually be exhausted, leading toplant death.

In operation, the apparatus 100 can be used routinely with mowing. Theapparatus 100, nonetheless, can be employed separately as well as aself-propelled walk behind or ride on unit. In one embodiment theapparatus 100 is used concurrently with mowing such as, for example, asan integrated part configured as a mower attachment, mounted in front,mid-section or rear of an existing mower. This includes ganged units,self-powered pull-behind units, and power take off driven, three pointhitch mounted or pull-type units for tractors. Alternatively, theintegrated part can be designed integral as part of the existing ornewly designed mower deck.

While certain configurations of structures have been illustrated for thepurposes of presenting the basic structures of the present invention,one of ordinary skill in the art will appreciate that other variationsare possible which would still fall within the scope of the appendedclaims. For example, the direction of rotation of the secondlongitudinal axis, orientation of the base blade, variations in thegeometries of the brush and its bristles and/or other protrusions toimpart wear, depth and/or width of grooves and/or rotating verticallyoriented slicing discs, spacing between brushes/knives, number anddimension of bristles/knives and grooves/rotating vertically orientedslicing discs, are contemplated. Additional advantages and modificationswill readily occur to those skilled in the art. Therefore, the inventionin its broader aspects is not limited to the specific details andrepresentative embodiments shown and described herein. Accordingly,various modifications may be made without departing from the spirit orscope of the general inventive concept as defined by the appended claimsand their equivalents.

What is claimed is:
 1. A method of applying a desired amount ofmechanical abrasion to desirable plants and undesirable plants,comprising: periodically applying mechanical abrasion to the desirableplants and the undesirable plants, wherein the level of mechanicalabrasion is selected to be damaging to the undesirable plants andsubstantially within a wear tolerance of the desirable plants.
 2. Themethod of claim 1, wherein the desirable plants comprise turfgrasses. 3.The method of claim 1, wherein the desirable plants comprise foragegrasses.
 4. The method of claim 1, wherein the mechanical abrasion isapplied by: a rotating cylindrical brush with bristles; and a basehaving a plurality of grooves; wherein the rotating cylindrical brush isspaced from the base such that the bristles engage the plurality ofgrooves, and the bristles cooperate with the grooves to abraid thedesirable and undesirable plants.
 5. The method of claim 1, wherein theperiod of applying mechanical abrasion is about once per week.
 6. Themethod of claim 1, wherein the period of applying mechanical abrasion isvaried to adjust for weed pressure.
 7. The method of claim 1, whereinthe mechanical abrasion is applied by: a rotating cylindrical brush withbristles; and a plurality of vertical walls extending from a base;wherein the rotating cylindrical brush is spaced from the base such thatthe bristles rub along the plurality of vertical walls to abraid thedesirable and undesirable plants.
 8. An apparatus for applying a desiredamount of mechanical abrasion to desirable plants and undesirableplants, comprising: wear means for applying mechanical abrasion to thedesirable plants and the undesirable plants, wherein the level ofmechanical abrasion is selected to be damaging to the undesirable plantsand substantially within a wear tolerance of the desirable plants;height means for adjusting a height of the wear means relative to thedesirable plants and the undesirable plants.
 9. The apparatus of claim8, wherein the wear means comprises: a rotating cylindrical brush withbristles; and a base having a plurality of grooves; wherein the rotatingcylindrical brush is mounted on the apparatus and spaced from the basesuch that the bristles progress through the plurality of grooves as thecylindrical brush is rotated.
 10. The apparatus of claim 8, wherein thewear means comprises: a rotating cylindrical brush with bristles; and aplurality of vertical walls extending from a base; wherein the rotatingcylindrical brush is mounted on the apparatus and spaced from the basesuch that the bristles rub along the plurality of vertical walls.